Ferroelectric Activity on Organic Crystal Trichloroacetamide

Dielectric constants and D - E hysteresis loops have been measured on trichloroacetamide (TCAA) single crystals. Only along the crystallographic b -axis are remarkable dielectric anomalies found at T C =354.6 K and T I =356.9 K upon heating. The Curie-Weiss relation holds in the high-temperature phase with a very small Curie constant of about 5.6 K. Typical ferroelectric D - E hysteresis loops are observed only in a limited temperature range of a few degrees just below T C ; the spontaneous polarization P s and the coercive field E c are estimated to be about 0.2 µC/cm 2 and 4 kV/cm, respectively, at 350 K. Since the E c steeply increases with decreasing temperature, it is difficult to reverse the P s at room temperature. Some discussions are presented for the causes of the weak ferroelectricity on TCAA.